Heretofore, it has been commonly performed to detect by a sensor vibration of a tap water pipe caused by water leakage therefrom. For example, Patent Document 1 discloses a leakage detector in which a detection unit incorporating a piezoelectric element and a base made of a rigid material are coupled together through a rubber material. This Patent Document mentions that a low-frequency vibration transmitting through a synthetic resin pipe can be amplified by means of resonance. It also mentions that a leakage location can be identified by installing two detectors in a fire hydrant or the like provided in a tap water pipeline, and analyzing an obtained correlation waveform.
Further, there has heretofore been a system capable of managing a flow rate at a remote location, such as a centralized meter reading system for tap water in a multidwelling or the like. For example, Patent Document 2 discloses a wireless meter reading system configured to eliminate needless receiving in a child wireless device to thereby extend battery life. This system is designed to wirelessly transmit information about flow rate to a remote location by using a battery.
Patent Document 3 discloses a pipe inspection apparatus using a piezoelectric ultrasonic transducer. This technique makes it possible to inspect a laying state of lining from outside a pipe.